The present invention relates to a toner cartridge which is set in an image forming apparatus like a copy machine, a printer, or the like and is replaceable, and particularly to a toner cartridge of a type which drops and feeds toner toward the apparatus body through a toner supply port provided immediately under an auger.
In general, in an image forming apparatus such as a copy machine and a printer, a toner cartridge filled with toner is set to be replaceable. The toner cartridge includes a long narrow cylindrical container body containing toner and is set at a predetermined position in the apparatus body such that the lengthwise axis of the container body extends in a substantially horizontal direction.
A toner supply port for dropping toner contained in the container body in the gravitational direction to feed toner to the apparatus body is formed at a bottom portion of the container body which is set laterally. Also, an auger extending immediately above the toner supply port along the lengthwise axis of the container body is provided in the container body. The auger comprises a rotary shaft including a spiral blade which feeds the toner contained in the container body toward the toner supply port.
For example, in case where the toner supply port is formed at a position distant from an end portion of the container body in its lengthwise direction to the center, the spiral directions of spiral blades provided on the rotary shaft of the auger are opposed to each other with respect to a position immediately above the toner supply port as a boundary, and the rotary shaft of the auger is rotated in a predetermined direction, so the toner in the container is collected from both sides to the toner supply port.
However, in this case, at a connecting portion of the blades formed along the rotary shaft in the opposite direction, i.e., at a portion of the auger immediately above the toner supply port, no spiral blade is formed and the rotary shaft is exposed therefrom to drop toner smoothly toward the container body through the toner supply port. As a result, a problem arises in that toner drops through the toner supply port by its dead weight even when the auger is not being rotated. If toner drops thus toward the apparatus body by dead weight even when the auger is not being rotated, it is not possible to achieve fixed-amount supply of toner based on the feed capability depending on the speed of rotation of the auger, so the supply amount of toner cannot be controlled stably. As a result, the supply amount of toner is not stable.